The objectives of this research proposal are to define some of the factors which regulate the synthesis of bile acids in health and disease. The diseases to be studied are neonatal cirrhosis, cholestasis, and adult patients with cirrhosis and cholestasis. The objectives will include: 1) to determine if the normal pathway to cholic acid synthesis takes place exclusively via 3 alpha, 7 alpha, 12 alpha-trihydroxy-5 beta-cholestan-26-oic acid (THCA), or if other metabolic routes are involved, 2) to determine if metabolic defects in the synthesis of bile acids are trasmitted in a genetic fashion or are the result of defects or toxins, and 3) to determine if the colonic administration of taurine conjugated THCA will result in cirrhosis in experimental animals and to determine if treatment of patients with metabolic defects will prevent their development of liver disease.